Preparation of cellulose nitroacetate with nitro-cellulose



Patented Nov. 20, 1934 UNITED STATES Cyril J. Stand, Rochester, N. Y.,and Charles E. Waring, Dayton, Ohio, assignors to Eastman Kodak Company,Rochester, N. Y., a corporation of NewYork No Drawing. ApplicationDecember 31, 19 30, v Serial No. 505,958

6 Claims. (cl. 260101) This invention relates to a process of formingcellulose-nitro-acetate by acetylating cellulose in the presence ofnitro-cellulose which acts asa nitrating agent, in the presence of asolvent for nitro-cellulose, containing chloracetic acid, acetone, orthe like.

An object of our invention is the preparation of a nitro-acetatederivative of cellulose by the use of cellulose nitrate as a nitratingagent. Al-

10 though cellulose nitro-acetates have been prepared through the use ofa variety of processes and nitration media, at no point has the use ofcellulose nitrate as the nitrating agent been contemplated. No previousprocess has included the novel idea of exchanging some of the nitrateradicals of nitrocellulose for acetyl groups and simultaneously usingthese nitrate groups to nitrate the cellulose present in the reactionmixture. By the use of cellulose nitrate as the nitrating agent it makespossible a variation of proportions in predetermined quantities so thatthe nitroacetate produced will be that desired by the operator. Theconditions under which the cellulose nitrate might be used involved aconsiderable problem and required a rather extended experimental studyto evolve conditions under which this reaction could be brought about.Addition of cellulose nitrate per se together with celluloseto theformation of irreversible gels when the cel-' 40 lulose nitrate wasadded at the close of the acetylation. It was found by us that thesolvents tried were unsuitable for the process due to the low watertolerance of the cellulose nitrate. Consequently the investigation wasdirected toward the trial of other solvents which were more energetic intheir solvent action on the cellulose nitrate and solutions of whichwere capable of existing in the presence of a few per cent. of water.Among such solvents acetone and chloracetic acid were tried, both ofwhich have proved satisfactory for this purpose, the chloracetic acidprobably being the more satisfactory of the two. since the color of thefinal dope is better. It has also been found desirable to have aceticacid present mixed with the solvent, this mixture being used todissolvethe cellulose nitrate} In practice the solvent may be added tothe acetic acid solution of the cellulose nitrate, or the cellulosenitrate may be added, dissolved in chloracetic acid or acetone solution,the acetic anhydride being'thereafter added.

Another object of the invention is to prepare a cellulose derivative,specifically a Intro-acetate which is'soluble in acetone even when notsubj ected to hydrolysis subsequent to the acetylation.Theproduct'formed in Example III, given below, is soluble in acetonefollowing acetylation, although a very short hydrolysis subsequent tothe acetylation gives theproduct a better acetone solubility. .Thisprocess involves the addition of fuming nitric acid as an aid to thenitration of the cotton linters by the cellulosenitrate and in thismanner additional nitration'will take place. Examples I and II do notcontemplate the addition of the fuming nitric acid. For instance, if theoperator wishes a product of low nitrogen content, fuming nitric acid isnot added, but on the other hand, if a nitro-acetate of a highernitrogen content is desired, the procedure in Example III is followed inwhich ahigher nitrogen content is found in the resulting product thanwould be obtained by exchange of nitrate and acetate radicals. I i

The specific exampleswhich follow illustrate the application of ourinvention to the formation of cellulose nitrate-acetates by thenitration of ce1lulose, with cellulose nitrate as the nitrating agent.

Example I About five pounds of a dope composed of cellu-' losenitrate-containing approximately 12% nitrogen in solution in acetic acidin the ratio of 1 part of nitrocellulose to 12 parts of acetic acid-wasdissolved in a mixture of about" 17 to 20 pounds of acetic acid, about 5pounds chloracetic'ac-id, and about 45 cc. of acatalyst consisting ofsulphuric and phosphoric acid in the proportionof 1:3. To this solutionis added from 2 to 5 pounds of cotton linters. The whole is allowed tostand at room temperature for about 15 hours (20-25 C At the. end ofthis time it was placed in a mixer and about 7-10 pounds of aceticanhydride were added. The outside temperature was maintained from 50 to80 F. for about two hours, about 80 to: F. for approximately 5 hours,and about 100 to 130 F. for about sixteen hours, when a clear dope wasobtained free from grain and fiber. The outside temperacellulose esterwas completely soluble in acetone.

If desired, the material may be then precipitated, Washed and dried- Theproduct was found to be soluble in acetone, chloroform, ethylenedichloride, ethyl acetate and 1.4-dioxan and to contain .69% nitrogen.

Example II j About /g pound of cellulose nitrate containingapproximately 12% nitrogen'isdissolved in about 800 grams of acetone andis then thoroughly I: at this temperature for 15 to 22 hours.

i 5 pounds chloracetic acid and pound of water.

mixed with from .15 to 20 pounds of acetic acid and from 40-50 cc. of amixed catalyst composed of sulphuric and phosphoric acids in the proportion of 1:3; from 2-5 pounds of cellulose linters are then added and thewhole mass is allowed to stand at room temperature'for from '15 to 20hours. The material is then placed in aivmixer andcooledto'approximately 60 F. and from 5 to 10 pounds of 85% aceticanhydride are added. The temperature of about 60 F. is maintained from 1to 3 hours and was then raised to about F. and held at that point. Thistemperature is maintained for about '7 to 12 hours, or until a dope freefrom grain'results. About 1500 to 2000 c. c. of a mixture of acetone andwater in the ratio of 9: 1 was added to hydrolyze the excess anhydrideQA hydrolysis mixture composed of about 600 c. c. of water and about 3liters of molten chloracetic acid is then added and the material ishydrolyzed for from 50' to '75 hours at about 120 F. or' until a testsample showed the product to be soluble in acetone. The material maythen be precipitated, washed and dried in the usual manner. The productis soluble in acetone, ethyl acetate, chloroform, chloroformalcohol, 1:4vdioxan, and ethyl oxalate, and contains 1.04% nitrogen.

- Example III About 5 pounds of a solution of cellulose nitrate inacetic acid, having approximately 12 parts oi acetic acid to 1 ofcellulose nitrate, was mixed with about 13 pounds acetic acid, about 5pounds chloracetic acid, and about 45 c. 0. mixed catalyst (phosphoricand sulphuric acids in the proportion of 1 to 3) until a homogeneousdope was obtained. From 2 to 5 pounds cotton linters were then suspendedin-this dope and allowed to stand at room temperature for from 15 to 20hours. The material was then transferred to a mixing apparatus and from5 to 10 pounds acetic anhydride was added. The temperature was kept atabout 20 C. When the mass became pasty a solution of about 200 c. c.fuming nitric acid in about 500. c. c. of acetic acid was slowly added.A very grainy dope resulted. The temperature was slow-- ly raised toabout 30 to 50 C. and maintained The prodnot at this point is soluble inacetone. it is preferred to subject the mixture to hydrolysis and ahydrolysis mixture of about the' follo'wing proportions was added: 48 c.c. hydrochloric acid,

However,

The hydrolysis was continued for from 25 to 40 hours at about 38 C. oruntil a nicely acetonesoluble product was procured. The material wasthen precipitated, washed, and dried in the usual manner. Analysis ofthis product showed 3.57% nitrogen.

Broadly our invention consists in the addition of cellulose to cellulosenitrate in a solvent which will make possible the nitration of thecellulose by the cellulosenitrate and then by use of acetic anhydride acellulose nitroacetate is formed. One of the features of this inventionis that some of the nitrate radicals are transferred from the cellulosenitrate to the cellulose and then upon acetylation the remainingavailable hydroxyl groups of the de-nitrated cellulose and those of thefreshly nitrated cellulose are taken up by acetylgroups. It isunderstood that other known acetylation catalysts may be used than theone shown'and that it is within the scope of this invention to applythis novel procedure to any acetylation reaction the onlycondition beingthat considerable =solvent be. present, together with the cellulosenitrate. I

Any solvent maybe used in this process which answers the requirementsgiven previously, namely, a good solvent of nitrocellulose and itsnitrocellulose solutions which must be capable of existing in afew percent of water. Some further examples of this type of solvent aredichloracetic acid, ethoxy acetic acid or methoxy acetic acid, or methylethyl "ketone.

What we claim as our invention and desire to secure by Letters Patent ofthe United States is:

1. A process of making cellulose nitro-acetate whichcom-prisesintrodu'cing cellulose into a solution comprisingcellulosenitrate and chloracetic acid and acetylating the resulting cellulosicmixture.

2. A process of making cellulose nitro-acetate which comprisesintroducing cellulose into a solution comprising cellulose nitrate andacetone and acetylating the resulting cellulosic mixture.

3. A process of making cellulose nitro-acetate which comprisesintroducing cellulose into cellulose nitrate in a solvent selected fromthe group consisting of the chlor-substituted acetic acids, the alkoxysubstituted acetic acids and acetone and then acetylating the resultingmixture.

4. A process of making cellulose nitro-acetate ing the cellulosederivative formed with fuming.

nitric acid. I I 5. A process of making cellulose nitro-acetate whichcomprises'introducing cellulose into a solution comprising cellulosenitrate and ethoxy acetic acid and acetylating the resulting cellulosicmixture.

6. A process of making cellulose nitro-acetate which comprisesintroducing cellulose into a solution comprising cellulose nitrate andacetone, 4

acetylating the resulting cellulosic mixture, and treating the cellulosederivative formed with fuming nitric acid.

. CYRIL J. STAUD.

CHARLES E. WARING.

